Growing Annual Flowers in Containers


The choice of container will depend largely upon three factors:

  • The size and style of the container (formal terra cotta with rolled rims, decorated concrete, rustic wood, etc.) should be suitable for the plants you wish to grow.
  • The container size and style also should be suitable for the design and scale of the location where the container will be sited (e.g., formal entrance, wooden deck, etc.)
  • The building materials (terra cotta, wood, concrete, plastic, etc. (will affect the weight, strength and weather hardiness of the container. For example, terra cotta pots absorb water and should not be kept outdoors, if filled or wet, during winter. Wood and well drained plastic or rubber containers are fine for year round outdoor use.


For best results, outdoor containers generally should have holes at the bottom for drainage. Most of the containers that we offer already have drain holes. However, if your container does not, you can easily add them using a regular drill bit (for plastic, wood, fiberglass, or molded resin) or masonry drill (for terra cotta with a “punch out” hole or for concrete).


The colors of all wood planters can be modified easily with stain, bleaching oils or paint. Nearly all wood finishes (except creosote) are safe for plants once dry. Check labels for naturally and quickly. If desired, however, terra cotta and concrete pots can be ‘aged’ by rubbing them with horse manure, moss, soil, buttermilk, tobacco juice and similar organic materials. When the containers are left outside, these organic materials will provide a growth medium for algae and lichens.


These easy steps provide good results:

  1. Cover the drain hole(s) with window screen mesh or week barrier fabric or fill the bottom 1-2” of the pot with coarse gravel or broken terra cotta, and then a ½” layer of fine gravel or sand. This will keep soil from leaking out of the container.
  2. Fill the container about one-third of the way with pre-moistened, medium weight potting mix (for most annuals and other plants).


Here are some suggestions for planting:

  1. Annual flowers and other source container plantings look best when the plants are tightly spaced, to achieve a lush, “spilling over’ effect. Remember: Annuals have only 4-5 months to grow and look their best, so they should be planted closely to provide more flowers and a lush appearance.
  2. In general, the taller the container, the higher the planting should be at the center.
  3. Smaller round pots – (up to 12” diameter or so) usually look best when tightly planted with one flower color and variety. Larger pots look effective with either larger annuals of one variety (e.g., Geraniums), or one or two taller varieties at center, and an edge planting of a draping annual of a contrasting or complementary hue. A “cottage” planting of mixed annuals also can be very striking; these generally work best with simple or rustic (not formal) container styles, and the flowers usually should be smaller and with more subtle or shaded hues.
  4. Space plants in the container tightly. Annuals only grow for one season, so plants can and should be placed tightly for a lush appearance. Use your hands to create soil pockets for planting. Before planting, loosen any matted roots around the edge of the plant’s soil ball.
  5. Keep the top of the rootballs and potting soil about ½” below the rim of the container, to facilitate watering.
  6. Water the container well after planting.
  7. Fertilize with Osmocote (slow release pellets), or with Miracle Gro or Peters Soluble Fertilizers for flowering plants.
  8. Check the container frequently to see if they need water, particularly during hot weather. Smaller containers may need water almost every day, while larger containers may require water every 3-4 days or so.


We offer a wide range of window boxes, window box liners, hanging baskets, pots and planter brackets. Please feel free to ask for help in selecting the right containers for your location.

© Rosedale Nurseries, Inc. 1993, 2003